can I connect 2 transfer switches to one service panel
- Thread starter Roach
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Do you have a wiring diagram of what you are proposing in order to avoid any misunderstanding including an explanation of the operation sequence.
I do not have any specifics really about the application except that my frriend would like to use 2 seperate generators at his house to power the house when there is a power outage.
My concern is this: can you connect 2 generators with two seperate transfer switch boxes (1 generator to each transfer box using these at 1 150 amp panel
My concern is this: can you connect 2 generators with two seperate transfer switch boxes (1 generator to each transfer box using these at 1 150 amp panel
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
As long as the two transfer switches are feeding two different 150A subpanels, so that any panel and its set of loads is only powered by one generator, it should be OK.
(But there are restrictions on how much load can be automatically transferred to that generator based on its rated output, so manual transfer switches may be necessary or else some form of automatic load shedding.)
If you want to have a third transfer switch to choose which generator will be used or want to try to parallel the two generators to a single panel and its set of loads, it will not work without a lot more gear or generators capable of being paralleled.
With only two transfer switches you could have POCO and one generator going into one transfer switch and the output of that transfer switch going to the second xfer switch along with the second generator. That would only allow you to use one generator at a time but would not require moving wires or plugs around to select which one.
qcroanoke
Sometimes I don't know if I'm the boxer or the bag
- Location
- Roanoke, VA.
- Occupation
- Sorta retired........
http://forums.mikeholt.com/showthre...2+ttransfer+switches+two+generators+one+panel
Read this thread. It even has a pic of what you are talking about.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
That is a very particular form of transfer switch that manually transfers one circuit from the main panel at a time to an assigned generator. This might work for the OP, but I don't think it was what he was planning to do.
If the OP wants to have the transfer switch control the input to the entire panel rather than individual circuits, the setup in the picture is not relevant.
qcroanoke
Sometimes I don't know if I'm the boxer or the bag
- Location
- Roanoke, VA.
- Occupation
- Sorta retired........
GoldDigger,
It reads as if he has the switches shown in the picture. Or at least something similar.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
I missed the "10 circuit" part of the original post. Thank you!
renosteinke
Senior Member
- Location
- NE Arkansas
I really don't like the idea of multiple transfer switches. How will you prevent back-feeding? How will you synchronize the waveforms?
Only an arrangement where each panel can be fed by only two sources, on an either-or arrangement, would work. I don't see any way to have three spurces of power available to the same panel.
Only an arrangement where each panel can be fed by only two sources, on an either-or arrangement, would work. I don't see any way to have three spurces of power available to the same panel.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
The transfer switch assemblies shown in the picture are an an exception in that they are wired to the load side of each individual branch circuit breaker. Each individual branch circuit will only be d able to be associated with one alternate energy source, eliminating cross connect problems. (Although you do have to be careful to use one of the handle-tied transfer switch pairs for 240 volt circuitsj. and you need to use common sense when dealing with MWBCs.
Why manual transfer switches
Why manual transfer switches
Thanks all of the info has been very helpful. I would have preffered him to just get one larger Genn. but he is who he is.
Can anyone tell me why I need to use a manual transfer switch box as opposed to automatic?
To recap , we will use the main panel and add a subpanel , one transfer box at each panel (Main & Subpanel) both panels will be 150 amps
we will have one Genn connecting to each reliance auto transfer switch (10 circuits) each
Each transfer switch will have seperate loads.
Genn supply will be 2 T30 plugs (1 to each transfer box.
Any thoughts , especially concerning manual vs: auto transfer box?
Why manual transfer switches
Thanks all of the info has been very helpful. I would have preffered him to just get one larger Genn. but he is who he is.
Can anyone tell me why I need to use a manual transfer switch box as opposed to automatic?
To recap , we will use the main panel and add a subpanel , one transfer box at each panel (Main & Subpanel) both panels will be 150 amps
we will have one Genn connecting to each reliance auto transfer switch (10 circuits) each
Each transfer switch will have seperate loads.
Genn supply will be 2 T30 plugs (1 to each transfer box.
Any thoughts , especially concerning manual vs: auto transfer box?
qcroanoke
Sometimes I don't know if I'm the boxer or the bag
- Location
- Roanoke, VA.
- Occupation
- Sorta retired........
article 702.5 1&2 explains it very well.
eHunter
Senior Member
- Location
- North Texas & Georgia
I don't believe Reliance Controls manufactures an Automatic Transfer Switch(ATS).
An ATS is prohibited because your genset(s) cannot automatically accept the entire house or full load when the utility fails unattended.
Read all of 702, much will apply to your installation.
Last edited:
shortcircuit2
Senior Member
- Location
- South of Bawstin
It sounds like in your application that it is also important that your generators do NOT have a neutral to ground bond at the gen-sets...
qcroanoke
Sometimes I don't know if I'm the boxer or the bag
- Location
- Roanoke, VA.
- Occupation
- Sorta retired........
Because by code an automatic transfer switch MUST be connected to a generator that is capable of handling the load transferred to it. (Automatically) so if you have 20 kva of load and a generator sized at 10 kva the install is illegal by code.
But
If you have a manual transfer switch under the same circumstances the NEC allows it because the homeowner is standing in front of the MTS to transfer the load and the NEC thinks the homeowner should have enough smarts to turn off what the generator can't run.
And if he doesn't the generator will let him know real quick.
MichaelKelley
Member
Yes, you can connect two transfer switches to one service panel, but you need to be very careful with that as everyone is telling you without any proper diagram, which may be helpful for you if explained diagrammatically.
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